System and Method for Scalable Digital Communications with Adaptive System Parameters

ABSTRACT

A method for operating an adapting device includes selecting a first access mode out of a plurality of access modes for a first transmission between a first communications device and a second communications device, wherein the selection of the first access mode is made in accordance with an access mode criterion, and at least one of communications system information, and user equipment information, and determining sparse code multiple access (SCMA) parameters from the first access mode in accordance with a SCMA parameter mapping rule. The method also includes providing information about the first access mode to at least one of the first communications device and the second communications device.

This application is a continuation of U.S. patent application Ser. No.14/453,875, filed Aug. 7, 2014, entitled “System and Method for ScalableDigital Communications with Adaptive System Parameters,” which claimsthe benefit of U.S. Provisional Application No. 61/863,213, filed onAug. 7, 2013, entitled “System and Method for Scalable Sparse CodeMultiple Access with Adaptive System Parameters,” which applications arehereby incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates generally to digital communications, andmore particularly to a system and method for scalable digitalcommunications with adaptive system parameters.

BACKGROUND

Different radio access techniques exist for different purposes orapplications. However, there is no general framework and mechanism toput them under the same umbrella and switch among them depending on therequirements of particular situations. These techniques include sparsecode multiple access (SCMA), multicarrier modulations such as orthogonalfrequency division multiplexing (OFDM), downlink (DL) usersuperposition, non-orthogonal multiple access (NOMA), code divisionmultiple access (CDMA), uplink (UL) multi-user multiple-inputmultiple-output (MU-MIMO), low density signature (LDS).

SUMMARY OF THE DISCLOSURE

Example embodiments of the present disclosure which provide a system andmethod for scalable digital communications with adaptive systemparameters.

In accordance with an example embodiment of the present disclosure, amethod for operating an adapting device is provided. The method includesselecting, by the adapting device, a first access mode out of aplurality of access modes for a first transmission between a firstcommunications device and a second communications device, wherein theselection of the first access mode is made in accordance with an accessmode criterion, and at least one of communications system information,and user equipment information. The method also includes determining, bythe adapting device, sparse code multiple access (SCMA) parameters fromthe first access mode in accordance with a SCMA parameter mapping rule,and providing, by the adapting device, information about the firstaccess mode to at least one of the first communications device and thesecond communications device.

In accordance with another example embodiment of the present disclosure,a method for operating a first device is provided. The method includessending, by the first device, user equipment information to a seconddevice, wherein the user equipment information comprises at least one ofuser equipment requirements and user equipment capability, andreceiving, by the first device, information about sparse code multipleaccess (SCMA) parameters related to an access mode for a transmissionbetween the first device and a third device, wherein the access mode isselected out of a plurality of access modes in accordance with an accessmode criterion, and at least one of the user equipment information andcommunications system information. The method also includescommunicating, by the first device, with the third device in accordancewith the access mode.

In accordance with another example embodiment of the present disclosure,an adapting device is provided. The adapting device includes aprocessor. The processor selects a first access mode out of a pluralityof access modes for a first transmission between a first communicationsdevice and a second communications device, wherein the selection of thefirst access mode is made in accordance with an access mode criterion,and at least one of communications system information, and userequipment information. The processor also determines sparse codemultiple access (SCMA) parameters from the first access mode inaccordance with a SCMA parameter mapping rule, and provides informationabout the first access mode to at least one of the first communicationsdevice and the second communications device.

In accordance with another example embodiment of the present disclosure,a user equipment is provided. The user equipment includes a transmitter,a receiver, and a processor operatively coupled to the transmitter andto the receiver. The transmitter sends user equipment information to afirst communications device, wherein the user equipment informationcomprises at least one of user equipment requirements and user equipmentcapability. The receiver receives information about sparse code multipleaccess (SCMA) parameters related to an access mode for a transmissionbetween the user equipment and a second communications device, whereinthe access mode is selected out of a plurality of access modes inaccordance with an access mode criterion, and at least one of the userequipment information and communications system information. Theprocessor communicates with the second communications device inaccordance with the access mode.

One advantage of an embodiment is that access modes may be adapted tomeet access mode criteria, as well as requirements and/or capabilitiesof the communications system and UE.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure, and theadvantages thereof, reference is now made to the following descriptionstaken in conjunction with the accompanying drawing, in which:

FIG. 1 illustrates an example communications system according to exampleembodiments described herein;

FIG. 2 illustrates an example SCMA multiplexing scheme for encoding dataaccording to example embodiments described herein;

FIGS. 3a and 3b illustrate example plots of SCMA system parametershighlighting complexity, multiplexing, spectral efficiency, andlink-budget trade-off according to example embodiments described herein;

FIGS. 4a, 4b, and 4c illustrate example plots of SCMA system parametershighlighting complexity, multiplexing, spectral efficiency, andlink-budget trade-off if overloading is capped to control complexityaccording to example embodiments described herein;

FIG. 5 illustrates an example high-level view of an example adaptingdevice according to example embodiments described herein;

FIG. 6a illustrates an example flow diagram of example operationsoccurring in an adapting device as the adapting device adaptivelyadjusts an access mode of a communications system (or a part thereof)according to example embodiments described herein;

FIG. 6b illustrates an example flow diagram of example operationsoccurring in a UE as the UE communicates according to exampleembodiments described herein;

FIG. 7 illustrates an example graphical mapping rule for downlink accessmode selection according to example embodiments described herein;

FIG. 8 illustrates an example graphical mapping rule for uplink accessmode selection according to example embodiments described herein;

FIG. 9 illustrates an example communications device according to exampleembodiments described herein; and

FIG. 10 illustrates an example communications device according toexample embodiments described herein.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The operating of the current example embodiments and the structurethereof are discussed in detail below. It should be appreciated,however, that the present disclosure provides many applicable inventiveconcepts that can be embodied in a wide variety of specific contexts.The specific embodiments discussed are merely illustrative of specificstructures of the disclosure and ways to operate the disclosure, and donot limit the scope of the disclosure.

One embodiment of the disclosure relates to scalable digitalcommunications with adaptive system parameters. For example, an adaptingdevice receives access mode criteria for a first communications channelbetween a communications controller and a user equipment, selects afirst access mode in accordance with a set of mapping rules to meet theaccess mode criteria, and provides information about the first accessmode to the communications controller and the user equipment.

The present disclosure will be described with respect to exampleembodiments in a specific context, namely SCMA communications systemsthat adaptively adjust their radio access mode for different access modecriteria. The disclosure may be applied to standards compliantcommunications systems, and non-standards compliant communicationssystems, that adaptively adjust their radio access mode for differentaccess mode criteria.

In SCMA, data is spread over multiple time-frequency tones of OFDMAresources through multi-dimensional codewords. Sparsity of codewordshelps to reduce the complexity of joint detection of multiplexed SCMAlayers by using message passing algorithm (MPA). In general, each layerof SCMA has its specific codebook set. Low density spreading (LDS) is aspecial case of SCMA. LDS as a form of multi-carrier CDMA (MC-CDMA) isused for multiplexing different layers of data. As opposed to SCMA withmulti-dimensional codewords, LDS uses repetitions of the same (QAM)symbol on layer-specific nonzero position in time or frequency. As anexample, in LDS-orthogonal frequency division multiplexing (LDS-OFDM) aconstellation point is repeated (with some possible phase rotations)over nonzero frequency tones of a LDS block. The shaping gain ofmulti-dimensional constellations is one of the advantages of SCMA overLDS. The gain is potentially high for higher order modulations where therepletion coding of LDS shows a large loss and poor performance.

SCMA is an encoding technique that encodes data streams, such as binarydata streams, or in general, M-ary data streams, where M is an integernumber greater than or equal to 2, into multidimensional codewords. SCMAdirectly encodes the data stream into multidimensional codewords andcircumvents quadrature amplitude modulation (QAM) symbol mapping, whichmay lead to coding gain over conventional CDMA (and LDS) encoding.Notably, SCMA encoding techniques convey data streams using amultidimensional codeword rather than a QAM symbol.

Additionally, SCMA encoding provides multiple access through the use ofdifferent codebooks for different multiplexed layers, as opposed to theuse of different spreading sequences for difference multiplexed layers,e.g., a LDS signatures in LDS, as is common in conventional CDMAencoding. Furthermore, SCMA encoding typically uses codebooks withsparse codewords that enable receivers to use low complexity algorithms,such as message passing algorithms (MPA), to detect respective codewordsfrom combined codewords received by the receiver, thereby reducingprocessing complexity in the receivers.

FIG. 1 illustrates an example communications system 100. Communicationssystem 100 may support SCMA communications. Communications system 100may include an evolved NodeB (eNB) 105 operating as a communicationscontroller. Communications system 100 may also include user equipment(UE), such as UE 110, UE 112, and UE 114. eNB 105 may include multipletransmit antennas and multiple receive antennas to facilitate MIMOoperation, wherein a single eNB may simultaneously transmit multipledata streams to multiple users, a single user also with multiple receiveantennas, or a combination thereof. Similarly, the UEs may includemultiple transmit antennas and multiple receive antennas to support MIMOoperation. In general, an eNB may also be referred to as acommunications controller, a NodeB, a base station, a controller, andthe like. Similarly, a UE may also be referred to as a mobile station, amobile, a terminal, a user, a subscriber, and the like. Communicationssystem 100 may also include a relay node (RN) 118 that is capable ofutilizing a portion of resources of eNB 105 to help improve coverageand/or overall performance of communications system 100.

An adapting device 120 may adapt access modes for communications system100 or a portion thereof. Adapting device 120 may adjust communicationssystem parameters of communications system 100 or a portion thereof tomeet access mode criteria to provide an access mode for devices incommunications system 100. A detailed discussion of adapting device 120is presented below. It is noted that although shown in FIG. 1 as being asingle stand-alone device, in other example embodiments, there may bemultiple adapting devices, each responsible for a different part of acommunications system. Alternatively, adapting device 120 may beco-located in other devices in communications system 100. As an example,some or all of the eNBs in communications system 100 may includeadapting devices.

While it is understood that communications systems may employ multipleeNBs capable of communicating with a number of devices, only one eNB,one RN, an adapting device, and a number of UEs are illustrated forsimplicity.

SCMA-OFDM is a code-domain multiplexing scheme over multicarriermodulation in which the spreading codebooks are sparse and hencedetection can be made simpler. Spreading factor, sparsity of codebooks,and number of the maximum SCMA multiplexed layers are communicationssystem parameters indicating the flexibility of the SCMA waveform.

FIG. 2 illustrates an example SCMA multiplexing scheme 200 for encodingdata. As shown in FIG. 2, SCMA multiplexing scheme 200 may utilize aplurality of codebooks, such as codebook 210, codebook 220, codebook230, codebook 240, codebook 250, and codebook 260. Each codebook of theplurality of codebooks is assigned to a different multiplexed layer.Each codebook includes a plurality of multidimensional codewords (orspreading sequences). It is noted that in LDS, the multidimensionalcodewords are low density sequence signatures. More specifically,codebook 210 includes codewords 211-214, codebook 220 includes codewords221-224, codebook 230 includes codewords 231-234, codebook 240 includescodewords 241-244, codebook 250 includes codewords 251-254, and codebook260 includes codewords 261-264.

Each codeword of a respective codebook may be mapped to a differentdata, e.g., binary, value. As an illustrative example, codewords 211,221, 231, 241, 251, and 261 are mapped to binary value ‘00’, thecodewords 212, 222, 232, 242, 252, and 262 are mapped to the binaryvalue ‘01’, the codewords 213, 223, 233, 243, 253, and 263 are mapped tothe binary value ‘10’, and the codewords 214, 224, 234, 244, 254, and264 are mapped to the binary value ‘11’. It is noted that although thecodebooks in FIG. 2 are depicted as having four codewords each, SCMAcodebooks in general may have any number of codewords. As an example,SCMA codebooks may have 8 codewords (e.g., mapped to binary values ‘000’. . . ‘111’), 16 codewords (e.g., mapped to binary values ‘0000’ . . . .‘1111’), or more.

As shown in FIG. 2, different codewords are selected from variouscodebooks 210, 220, 230, 240, 250, and 260 depending on the binary databeing transmitted over the multiplexed layer. In this example, codeword214 is selected from codebook 210 because the binary value ‘11’ is beingtransmitted over the first multiplexed layer, codeword 222 is selectedfrom codebook 220 because the binary value ‘01’ is being transmittedover the second multiplexed layer, codeword 233 is selected fromcodebook 230 because the binary value ‘10’ is being transmitted over thethird multiplexed layer, codeword 242 is selected from codebook 240because the binary value ‘01’ is being transmitted over the fourthmultiplexed layer, codeword 252 is selected from codebook 250 becausethe binary value ‘01’ is being transmitted over the fifth multiplexedlayer, and codeword 264 is selected from codebook 260 because the binaryvalue ‘11’ is being transmitted over the sixth multiplexed layer.Codewords 214, 222, 233, 242, 252, and 264 may then be multiplexedtogether to form multiplexed data stream 280, which is transmitted overshared resources of a network. Notably, codewords 214, 222, 233, 242,252, and 264 are sparse codewords, and therefore can be identified uponreception of multiplexed data stream 280 using a low complexityalgorithm, such as a message passing algorithm (MPA) or a turbo decoder.

According to an example embodiment, an access mode of a communicationssystem (or of a portion of a communications system) is be specified, atleast in part, by communications system parameters. The communicationssystem parameters, when set to specific values, may determine how thecommunications system communicates with UE within it. As an illustrativeexample, access modes in a SCMA communications system may be specifiedby a number of communications systems parameters, including:

M—a number of codewords in a SCMA codebook.

K—a spreading factor.

J—a maximum number of layers (or codebooks and/or signatures). It isnoted that the number of signatures may exceed this value if signaturereuse is allowed, such as in an uplink.

N—a number of nonzero elements of each codeword.

d_(f)—a maximum number of codewords colliding at a tone.

λ—an overloading factor.

l—a number of overlapping elements of any two distinct codebooks

Example values of the communications system parameters include:

$J = {\begin{pmatrix}K \\N\end{pmatrix}.}$

${d_{f} = {\begin{pmatrix}{K - 1} \\{N - 1}\end{pmatrix} = \frac{JN}{K}}},$

which determines the complexity of the MPA algorithm ∝M^(d) ^(f) .

$\lambda = {\frac{J}{K} = {\frac{d_{f}}{N}.}}$

max(0,2N−K)≦l≦N−1.

An example SCMA communications system design example is as follows:

${N = {{2\mspace{20mu} J} = {\begin{pmatrix}K \\N\end{pmatrix} = {\begin{pmatrix}K \\2\end{pmatrix} = \frac{K\left( {K - 1} \right)}{2}}}}};$

if K=4, then J=6.

${d_{f} = {\begin{pmatrix}{K - 1} \\{N - 1}\end{pmatrix} = {\begin{pmatrix}{K - 1} \\1\end{pmatrix} = {K - 1}}}},{{\forall J};}$

if K=4, then d_(f)=3.

${\lambda = {\frac{J}{K} = \frac{K - 1}{2}}};$

if K=4, then λ=4.

0≦l≦1 if K=4, which means that the codewords are either totallyorthogonal with no overlap (l=0) or they collide only over one non-zeroelement (l=1). Then, a factor graph of an SCMA codebook may be of theform:

$\begin{bmatrix}1 & 1 & 1 & 0 & 0 & 0 \\1 & 0 & 0 & 1 & 1 & 0 \\0 & 1 & 0 & 1 & 0 & 1 \\0 & 0 & 1 & 0 & 1 & 1\end{bmatrix}.$

According to an example embodiment, the communications systemsparameters of a communications system may be set so that the access modeof the communications system emulates that of another communicationssystem. As an illustrative example, a SCMA communications system may beset to emulate an orthogonal frequency division multiple access (OFDMA)communications system if communications system parameters K is set to 1(K=1) and N is set to 1 (N=1). As another illustrative example, a SCMAcommunications system may be set to emulate a CDMA communications systemif communications system parameters N and K are set to be equal (N=K)and non-zero elements are not allowed in the codebooks. The codebooksmay be constructed over quadrature amplitude modulation (QAM) symbolswith CDMA spreading signatures.

FIGS. 3a and 3b illustrate example plots of SCMA complexity,multiplexing, spectral efficiency, and link-budget trade-off. As shownin FIG. 3b , for a given N and K, complexity can be capped by limitingthe number of multiplexed layers. The cost for doing so may be a loweroverloading factor, as discussed below.

FIGS. 4a, 4b, and 4c illustrate example plots of SCMA if overloading iscapped to control complexity. As an example, complexity may be limitedby reducing the number of overlaid codewords.

According to an example embodiment, a SCMA communications system is usedto implement flexible and scalable access techniques that compromiseamongst criteria, e.g., spectral efficiency, coverage, detectioncomplexity, connectivity, link budget, and the like, to supportdifferent application scenarios and access modes under a singlecommunications system with a smooth switching mechanism. Theimplementation is achieved by selecting an access mode in accordancewith access mode criteria, communications system information, and UEinformation, and the selected access mode is implemented by setting SCMAparameters based on mapping rules and the selected access mode.

According to an example embodiment, a SCMA communications systemoptimizes access modes for different application scenarios and differentreceive categories. The optimization of the access modes is achieved byadjusting SCMA parameters. As an example, an access mode adaptationmechanism, having predefined access modes for both UL and DL, selects abest access mode in accordance with access mode criteria, such asapplications, requirements, network conditions, and the like.Additionally, signaling support is provided to switch between differentaccess modes. The SCMA communications system is adaptively adjustedaccording to access mode criteria. There is low signaling overhead toswitch the access mode and/or parameters in response to the access modecriteria.

In general, SCMA-OFDM is a flexible waveform that can facilitatedifferent access modes, including existing ones such as OFDMA, LDS-OFDM,UL MU-MIMO, and MC-CDMA. SCMA-OFDM also is a promising waveform/accesstechnology for proposed 5G standards and beyond. The access modes may beapplied to an individual transmission, a plurality of transmissions, asingle communications channel (uplink, downlink, or uplink anddownlink), or a plurality of communications channels.

FIG. 5 illustrates a high-level view of an example adapting device 500.Adapting device 500 may perform access mode/UE criteria processing 505on access mode criteria, which may include communications systemrequirements, and communications system capabilities, as well as UEcriteria, which may include UE capabilities and UE requirements. Theprocessed access mode criteria and/or the UE criteria may be provided toan adaptive framework 510 to select an access mode 515. Examples ofaccess mode criteria and/or UE criteria may include link-budget,coverage, connectivity, throughput, multiplexing gain, processingcapabilities, and the like. Adaptive framework 510 may utilize mappingrules to select values for communications system parameters (such as J,N, K, d_(f), λ, multiplexing technique, and the like) to emulate anaccess mode to meet the access mode criteria and/or the UE criteria.Examples of access modes include OFDMA, NOMA, single UE SCMA (SU-SCMA),multi-user SCMA (MU-SCMA), multi-carrier CDMA (MC-CDMA), low densitysignature (LDS), and the like.

Table 1 below illustrates example predefined downlink (DL) multipleaccess modes, in which J is a maximum number of signatures/codebooks, Kis a spreading factor, and N≦K is a number of non-zero elements in eachsignature/codeword.

TABLE 1 Example downlink multiple access modes. Codebook/ TypicalScenario J K N Signature Comment Applications SCMA- J ≦ f K > N N >> 1SCMA large processing Link budget and mode1 (N, K) multidimensional gaindue to large coverage codebooks, or effective improvement LDS signaturesspreading factor SCMA- Moderate K > N N > 1 SCMA User pairing CapacityMode2 multidimensional with power enhancement or codebooks, orallocation, Low interference LDS signatures to moderate whiteningoverloading factor SCMA- Large K > N N > 1 SCMA Large Scheduling freeMode3 multidimensional overloading small packet codebooks, or factortransmission for LDS signatures massive connectivity OFDMA 1 1 1 — Non-legacy UEs or UE superposition with no SCMA type decoding capabilitytransmission might fall into this category DL-NOMA J > 1 1 1 — User DLuser paring and (reuse) superposition open loop multiple with poweraccess for UEs with sharing SIC reception capability MC-CDMA J ≦ K K = NN > 1 Orthogonal or CDMA Coverage/link non-orthogonal signatures budgetCDMA allocated to one improvement with signatures or multiple UEsunder-loading

Table 2 below illustrates predefined uplink (UL) multiple access modesin which J is a maximum number of signatures/codebooks, K is a spreadingfactor, and N≦K is a number of non-zero elements in eachsignature/codeword.

TABLE 2 Example uplink multiple access modes. Codebook/ Typical ScenarioJ K N Signature Comment Applications SCMA- J ≦ f K > N N >> 1 SCMA largeprocessing Link budget Mode1 (N, K) multidimensional gain due to largeand coverage codebooks, or effective improvement LDS signaturesspreading factor SCMA- Moderate K > N N > 1 SCMA Moderate InterferenceMode-2 multidimensional overloading whitening and codebooks, or factormulti-user LDS signatures channel diversity for better capacity SCMA-Large K > N N > 1 SCMA Large Contention Mode-3 multidimensionaloverloading based small codebooks, or factor packet LDS signaturestransmission for massive connectivity OFDMA, 1 1 1 — Non- Legacy UEsSC-FDMA superposition and BSs with type no SCMA transmission decodingcapabilities might fall into this category. UL-NOMA J > 1 1 1 —Superposition UL multi-user (reuse) type access with transmissionnon-linear reception capability (SIC) at BS MC-CDMA J ≦ K K = N N > 1Orthogonal or CDMA For non-orthogonal signatures coverage/link CDMAallocated to one budget signatures or multiple UEs improvement to getprocessing gain

FIG. 6a illustrates a flow diagram of example operations 600 occurringin an adapting device as the adapting device adaptively adjusts anaccess mode of a communications system (or a part thereof). Operations600 may be indicative of operations occurring in an adapting device,such as a stand-alone adapting device or a co-located adapting devicelocated in a network device, such as an eNB, in the communicationssystem, as the adapting device adaptively adjusts the access mode of thecommunications system (or a part thereof).

Operations 600 may begin with the adapting device receivingcommunications system information (block 605). As discussed previously,the communications system information may include information aboutapplications, requirements, network conditions, and the like. Examplesof the communications system information may include communicationssystem requirements, and/or communications system capabilities, and thelike. The adapting device may receive the communications systeminformation from controller(s) or eNB(s) in the communications system,or another network entity in the communications system that maintainsthe access mode criteria.

The adapting device may receive UE information (block 607). Examples ofUE information may include UE capabilities, UE requirements, and thelike. The adapting device may receive the UE information from UE(s) thatit is serving, UE(s) in the communications system, a network entity inthe communications system that maintains the UE criteria.

The adapting device may receive communications system parameters (block610). The communications system parameters may include J, N, K, d_(f),λ, multiplexing technique, and the like. The adapting device may have adefault version of the communications system parameters provided to itat system start up, for example, and then as it (as well as potentiallyother adapting devices) adjusts the communications system parameters,the adapting device may receive (or provide) updates for thecommunications system parameters. Depending on a granularity of theadaptation (e.g., communications system wide, eNB wide, cell wide,eNB-to-UE type wide, eNB-to-UE pairing wide), the adapting device maystore different versions of the communications system parameters for thedifferent levels of granularity and devices involved.

The adapting device may receive access mode criteria (block 612). Theaccess mode criteria may include link-budget, coverage, connectivity,throughput, multiplexing gain, processing capabilities, and the like.According to an example embodiment, the access mode criteria may beassociated with a transmission(s) or a communications channel. Theaccess mode criteria may be associated with a single transmission over asingle communications channel, a plurality of transmissions over asingle communications channel, a plurality of transmissions over aplurality of communications channels, a single communications channel(such as a downlink communications channel between an eNB and a UE or anuplink communications channel between a UE and an eNB), or a pluralityof communications channels (such as both downlink and uplinkcommunications channels between an eNB and a UE, uplink and/or downlinkcommunications channels between an eNB and a type (or group) of UEs,uplink and/or downlink communications channels between a group of eNBsand a type (or group) of UEs, uplink and/or downlink communicationschannels between all eNBs and a type (or group) of UEs, uplink and/ordownlink communications channels between all eNBs and all UEs, and thelike).

The adapting device may receive mapping rules (block 615). The mappingrules may specify how the communications system parameter(s), e.g., SCMAparameter(s), are affected by the access mode criteria, thecommunications system information, and the UE information. The mappingrules may be associated with transmissions for downlink communicationschannels, uplink communications channels, or both downlink and uplinkcommunications channels. The mapping rules may differ for differenttypes or groups of UEs. The mapping rules may differ for one eNB ormultiple eNBs. The mapping rules may also specify how to change thecommunications system parameter(s) and potentially, by how much. As anillustrative example, parameter K may be impacted by UE that have noSCMA capability, while parameters K and J may be impacted by a need tosupport large number of overlaid transmissions in a massive connectivitysituation. Table 3 below illustrates example mapping rules.

TABLE 3 Example mapping rules. Acceptable No. Requirements/Capabilitiesaccess mode System parameters 1 Legacy users with no capabilities toOFDMA K = 1 and no super handle spreading in any forms as welltransmission positioning as no SIC reception capability mode 2 Legacyusers with no capability to OFDMA K = 1 and UE pairing handle spreadingin any forms but with transmission SIC reception capability mode anduser pairing (NOMA) 3 User can support spreading with linear MC-CDMA K >1 but no overloading reception techniques 4 This MC-CDMA user needslarger Increase K with limited J coverage and link budget 5 More MC-CDMAusers need to access Increase K and J the system to support massiveconsidering complexity connectivity for example for capability ofreceivers contention-based transmission 6 User can support SCMAspreading SCMA-OFDM SCMA codebooks with with advanced non-linearreception appropriate K, J, and d_(f) capabilities 7 This SCMA userneeds larger coverage Increase N only or both N and link budget and Kwhile limit J and consider complexity impacts. Increasing N improvesprocessing and multi-dimensional gain of SCMA codebooks. 8 More SCMAusers need to access the Increase K and J system to support massiveconnectivity considering complexity for example for contention-basedcapability of receivers by access controlling N. 9 Throughputimprovement for SCMA SCMA codebooks rather users than LDS signaturesIncrease N at the expense of more complexity Allow UE pairing if usersand network support UE pairing access mode (MU-SCMA) 10 SCMA users withlow PAPR Limit bandwidth of requirements for example for smalltransmission packet transmission of UL access or Use SCMA codebooks MTCproviding lower PAPR at the expense of possible less throughputperformance Reduce N to decrease PAPR with careful codebook design

The adapting device may select an access mode in accordance with themapping rules to meet the access mode criteria, the communicationssystem information, and the UE information (block 620). The adaptingdevice may select the access mode out of a plurality of access modes. Asan illustrative example, the adapting device may have a list of theplurality of access modes and the adapting device may select the accessmode out of the plurality of access modes. The adapting device mayselect the access mode from the plurality of access modes by consideringthe access mode criteria, the communications system information, and theUE information. As an illustrative example, if the UE is a legacy UEwith no SCMA capability, the adapting device may select OFDMA as theaccess mode. Similarly, if the UE is SCMA capable, the adapting devicemay consider access mode criteria, such as link-budget, coverage, andthe like, to select the access mode. Detailed discussions of exampleaccess mode selection techniques are presented below.

The adapting device may determine the communications system parameters,e.g., SCMA parameters, from the selected access mode in accordance withthe mapping rules (block 622). The adapting device may use mappingrules, such as the example mapping rules shown in Table 3, to determinevalues for communications system parameters from the selected accessmode. As an illustrative example, if the selected access mode for aspecified type of UE is to increase the coverage area for the UE, theadapting device may use mapping rule #7 shown in Table 3 and increaseparameter N only or both parameters N and K while limiting parameter Jand consider complexity impacts, since increasing parameter N improvesprocessing and multi-dimensional gain of SCMA codebooks.

The adapting device may signal the communications system parameters(block 625). The adapting device may send the communications systemparameters to devices impacted by the access mode change. As anillustrative example, if the access mode change is for thecommunications system as a whole, the adapting device may send thecommunications system parameters to the eNBs in the communicationssystem, which may provide the communications system parameters to theUEs that they serve. As another illustrative example, if the access modechange is for an eNB, the adapting device may send the communicationssystem parameters to the eNB and the eNB may provide the communicationssystem parameters to the UE that it serves. As yet another illustrativeexample, if the access mode change is for a single cell and UE type, theadapting device may send the communications system parameters to an eNBassociated with the cell and the eNB may provide the communicationssystem parameters to the UEs that it is serving that are of same UEtype. As yet another illustrative example, if the access mode change isfor a single cell and a single UE, the adapting device may send thecommunications system parameters to an eNB associated with the cell andthe eNB may provide the communications system parameters to the UE.According to an example embodiment, there may be a pre-defined pluralityof access modes and the adapting device may simply send an indicator,e.g., a number that corresponds to the selected access mode.

FIG. 6b illustrates an example flow diagram of example operations 650occurring in a UE as the UE communicates. Operations 650 may beindicative of operations occurring in a UE, such as UE 110, UE 112, andUE 114, as the UE communicates.

Operations 650 may begin with the UE sending UE information (block 655).The UE may send the UE information, including UE capabilities and/orrequirements, and the like. The UE information may be sent to an eNBserving the UE or an adapting device that is performing access modeselection. The UE may receive communications system parameters (block660). The UE may receive the communications system parameters from theeNB or the adapting device, whichever is performing access modeselection. The communications system parameters may be sent to the UE aswell as other devices that are impacted by the access mode selection.According to an example embodiment, there may be a pre-defined pluralityof access modes and the UE may receive an indicator, e.g., a number thatcorresponds to the selected access mode. The UE may communicate usingthe communications system parameters (block 665).

FIG. 7 illustrates an example graphical representation of a mapping rule700 for downlink access mode selection. The representation of mappingrule 700 shown in FIG. 7 may illustrate graphically the selection of anaccess mode for a downlink. The adapting device may select OFDMA 705 forthe downlink if the UE(s) are legacy UEs or if SCMA is not supported.Then, if coverage and/or link budget increase is an access modecriterion, the adapting device may select MC-CDMA 710. If capacityincrease is access mode criterion and the UE(s) has successiveinterference cancellation capability, the adapting device may selectDL-NOMA 715.

The adapting device may select SCMA 720 if the UE(s) and eNB(s) are SCMAcapable. Then if link-budget and coverage improvement are access modecriterion, the adapting device may select mode-1 SCMA 725. Ifinterference whitening and multi-user pairing for better capacity areaccess mode criterion, the adapting device may select mode-2 SCMA 730,and if scheduling free small packet transmission for massiveconnectivity is the access mode criteria, the adapting device may selectmode-3 SCMA 735.

FIG. 8 illustrates an example graphical representation of a mapping rule800 for uplink access mode selection. The representation of mapping rule800 shown in FIG. 8 may illustrate graphically the selection of anaccess mode for an uplink. The adapting device may select OFDMA orSC-FDMA 805 for the uplink if the UE(s) are legacy UEs and if SCMA isnot supported at the eNB(s). Then, if random access with moderateconnectivity or capacity enhancement if eNB has SIC reception, theadapting device may select UL-NOMA 810. If coverage and/or link budgetincrease are access mode criterion, the adapting device may selectMC-CDMA 815.

The adapting device may select SCMA 820 if the UE(s) and eNB(s) are SCMAcapable. Then, if link-budget and coverage improvement are access modecriterion, the adapting device may select mode-1 SCMA 825. Ifinterference whitening and multi-user pairing for better capacity areaccess mode criterion, the adapting device may select mode-2 SCMA 830,and if scheduling free small packet transmission for massiveconnectivity is the access mode criteria, the adapting device may selectmode-3 SCMA 835.

FIG. 9 illustrates an example first communications device 900.Communications device 900 may be an implementation of an adaptingdevice, such as a stand-alone device, or a co-located device located inan eNB, a communications controller, a base station, a controller, andthe like. Communications device 900 may be used to implement variousones of the embodiments discussed herein. As shown in FIG. 9, atransmitter 905 is configured to transmit packets, communications systemparameters, and the like. Communications device 900 also includes areceiver 910 that is configured to receive packets, access modecriteria, communications system parameters, mapping rules, and the like.

A criteria processing unit 920 is configured to process access modecriteria and communications system information, such as communicationssystem requirements, communications system capabilities link-budget,coverage, connectivity, throughput, multiplexing gain, and the like, tohelp adapt an access mode. Criteria processing unit 920 is configured toprocess UE information to help adapt the access mode. A parameterprocessing unit 922 is configured to receive processed access modecriteria, communications system information, UE information, andcommunications system parameters, and to select an access mode inaccordance with the access mode criteria, the communications systeminformation, and the UE information. Parameter processing unit 922 isconfigured to set the communications system parameters in accordancewith the mapping rules and the selected access mode. A memory 930 isconfigured to store packets, access mode criteria, communications systeminformation, UE information, communications system parameters, mappingrules, and the like.

The elements of communications device 900 may be implemented as specifichardware logic blocks. In an alternative, the elements of communicationsdevice 900 may be implemented as software executing in a processor,controller, application specific integrated circuit, or so on. In yetanother alternative, the elements of communications device 900 may beimplemented as a combination of software and/or hardware.

As an example, receiver 910 and transmitter 905 may be implemented as aspecific hardware block, while criteria processing unit 920 andparameter processing unit 922 may be software modules executing in amicroprocessor (such as processor 915) or a custom circuit or a customcompiled logic array of a field programmable logic array. Criteriaprocessing unit 920 and parameter processing unit 922 may be modulesstored in memory 930.

FIG. 10 illustrates an example second communications device 1000.Communications device 1000 may be an implementation of a receivingdevice, such as a user equipment, an eNB, and the like. Communicationsdevice 1000 may be used to implement various ones of the embodimentsdiscussed herein. As shown in FIG. 10, a transmitter 1005 is configuredto transmit packets, access mode criteria, mapping rules, and the like.Communications device 1000 also includes a receiver 1010 that isconfigured to receive packets, communications system parameters, and thelike.

A criteria processing unit 1020 is configured to process access modecriteria and communications system information, such as communicationssystem requirements, communications system capabilities link-budget,coverage, connectivity, throughput, multiplexing gain, and the like, andUE information, such as UE capabilities, UE requirements, and the like,to help adapt an access mode. A parameter processing unit 1022 isconfigured to receive information, such as communications systemparameters, associated with an access mode. A memory 1030 is configuredto store packets, access mode criteria, communications systeminformation, UE information, communications system parameters, and thelike.

The elements of communications device 1000 may be implemented asspecific hardware logic blocks. In an alternative, the elements ofcommunications device 1000 may be implemented as software executing in aprocessor, controller, application specific integrated circuit, or soon. In yet another alternative, the elements of communications device1000 may be implemented as a combination of software and/or hardware.

As an example, receiver 1010 and transmitter 1005 may be implemented asa specific hardware block, while criteria processing unit 1020 andparameter processing unit 1022 may be software modules executing in amicroprocessor (such as processor 1015) or a custom circuit or a customcompiled logic array of a field programmable logic array. Criteriaprocessing unit 1020 and parameter processing unit 1022 may be modulesstored in memory 1030.

Although the present disclosure and its advantages have been describedin detail, it should be understood that various changes, substitutionsand alterations can be made herein without departing from the spirit andscope of the disclosure as defined by the appended claims.

What is claimed is:
 1. A method for operating an adapting device, themethod comprising: providing, by the adapting device to at least one ofa first communications device and a second communications device,information about first sparse code multiple access (SCMA) parametersspecifying a first access mode out of a plurality access modes, for afirst transmission between the first communications device and thesecond communications device; and providing, by the adapting device tothe at least one of the first communications device and the secondcommunications device, information about second SCMA parametersspecifying a second access mode out of the plurality access modes, for asecond transmission between the first communications device and thesecond communications device.
 2. The method of claim 1, furthercomprising: selecting, by the adapting device, the first access mode inaccordance with an access mode criterion and at least one ofcommunications system information or user equipment information, anddetermining, by the adapting device, the first SCMA parameters from thefirst access mode in accordance with an SCMA parameter mapping rule. 3.The method of claim 2, wherein the communications system informationcomprises at least one of communications system capabilities andcommunications system requirements, and wherein the user equipmentinformation comprises at least one of user equipment capabilities anduser equipment requirements.
 4. The method of claim 2, wherein the SCMAparameters mapping rule defines a relationship between the first accessmode and values of the SCMA parameters.
 5. The method of claim 2,wherein the SCMA parameters mapping rule is predefined and stored in theadapting device.
 6. The method of claim 2, wherein the access modecriterion comprises at least one of communications system spectralefficiency, communications system coverage, communications systemdetection complexity, communications system connectivity, andcommunications system link budget.
 7. The method of claim 2, wherein thefirst transmission comprises an uplink transmission and a downlinktransmission, and wherein selecting the first access mode comprises:selecting a second access mode for the uplink transmission; andselecting a third access mode for the downlink transmission.
 8. Themethod of claim 2, further comprising selecting the first access mode inaccordance with a fourth access mode associated with a thirdtransmission sharing at least one network resource with the firsttransmission, wherein the first access mode is selected so that thefirst access mode does not conflict with the fourth access mode.
 9. Themethod of claim 1, wherein the first SCMA parameters comprise at leastone of M, K, J, N, l, λ, and d_(f), where M is a number of codewords ina SCMA codebook, K is a spreading factor, J is a maximum number oflayers, N is a number of nonzero elements in each codeword of a SCMAcodebook, l is a number of overlapping elements of any two distinctcodebooks, λ is an overloading factor, and d_(f) is maximum number ofcodewords colliding at a tone.
 10. The method of claim 1, wherein thefirst transmission comprises one of an uplink transmission and adownlink transmission.
 11. The method of claim 1, wherein providing theinformation about the first SCMA parameters comprises transmitting anindicator of the first access mode.
 12. The method of claim 11, whereinthe indicator is transmitted using one of semi-static messaging anddynamic messaging.
 13. A method for operating a first device, the methodcomprising: receiving, by the first device, information about sparsecode multiple access (SCMA) parameters specifying an access mode out ofa plurality of access modes, for a transmission between the first deviceand a third device; and communicating, by the first device, with thethird device in accordance with the access mode.
 14. The method of claim13, wherein the SCMA parameters are related to the access mode by anSCMA parameters mapping rule.
 15. The method of claim 13, wherein thefirst device is a user equipment.
 16. The method of claim 13, furthercomprising: sending, by the first device, user equipment information toa second device, wherein the user equipment information comprises atleast one of user equipment requirements and user equipment capability,and wherein the access mode is in accordance with an access modecriterion and at least one of the user equipment information andcommunications system information.
 17. The method of claim 16, whereinthe second device is an evolved NodeB and the third device is theevolved NodeB.
 18. The method of claim 16, wherein the second device isan adapting device and the third device is an evolved NodeB.
 19. Anadapting device comprising: a processor; and a non-transitory computerreadable storage medium storing programming for execution by theprocessor, the programming including instructions for: providing, by theadapting device to at least one of a first communications device and asecond communications device, information about first sparse codemultiple access (SCMA) parameters specifying a first access mode out ofa plurality access modes, for a first transmission between the firstcommunications device and the second communications device; andproviding, by the adapting device to the at least one of the firstcommunications device and the second communications device, informationabout second SCMA parameters specifying a second access mode out of theplurality access modes, for a second transmission between the firstcommunications device and the second communications device.
 20. Theadapting device of claim 19, wherein the programming includes furtherinstructions for: selecting the first access mode in accordance with anaccess mode criterion and at least one of communications systeminformation or user equipment information, and determining the firstSCMA parameters from the first access mode in accordance with an SCMAparameter mapping rule.
 21. The adapting device of claim 20, furthercomprising a receiver operatively coupled to the processor andconfigured to receive the user equipment information.
 22. The adaptingdevice of claim 20, wherein the first transmission comprises an uplinktransmission and a downlink transmission, and wherein the instructionsfor selecting the first access mode comprise further instructions for:selecting a third access mode for the uplink transmission, and selectinga fourth access mode for the downlink transmission.
 23. The adaptingdevice of claim 20, wherein the instructions for selecting the firstaccess mode comprise further instructions for selecting the first accessmode in accordance with a fourth access mode associated with a thirdtransmission sharing at least one network resource with the firsttransmission, wherein the first access mode is selected so that thefirst access mode does not conflict with the fourth access mode.
 24. Theadapting device of claim 19, further comprising a transmitteroperatively coupled to the processor and configured to transmit anindicator of the first access mode.
 25. The adapting device of claim 19,wherein the first SCMA parameters comprise at least one of M, K, J, N,l, λ, and d_(f), where M is a number of codewords in a SCMA codebook, Kis a spreading factor, J is a maximum number of layers, N is a number ofnonzero elements in each codeword of a SCMA codebook, l is a number ofoverlapping elements of any two distinct codebooks, λ is an overloadingfactor, and d_(f) is maximum number of codewords colliding at a tone.26. A user equipment comprising: a receiver configured to receiveinformation about sparse code multiple access (SCMA) parametersspecifying an access mode out of a plurality of access modes, for atransmission between the user equipment and a second communicationsdevice; and a processor operatively coupled to the receiver, theprocessor configured to communicate with the second communicationsdevice in accordance with the access mode.
 27. The user equipment ofclaim 26, wherein the SCMA parameters are related to the access mode bya SCMA parameters mapping rule.
 28. The user equipment of claim 26,further comprising a transmitter operatively coupled to the processorand configured to send user equipment information to a firstcommunications device, wherein the user equipment information comprisesat least one of user equipment requirements and user equipmentcapability, and wherein the access mode is in accordance with an accessmode criterion, and at least one of the user equipment information andcommunications system information.
 29. The user equipment of claim 28,wherein the first communications device is an evolved NodeB and thesecond communications device is the evolved NodeB.
 30. The userequipment of claim 28, wherein the first communications device is anadapting device and the second communications device is an evolvedNodeB.